The present invention relates generally to a steering wheel having an annular rim and at least one spoke through which the rim is connected to a central hub. More particularly, the present invention is concerned with an elongated blank for a core of a steering wheel rim, having recess or recesses, as viewed in section, which are sized to fit to end portions of spoke cores of different sizes. The invention is also concerned with a core of a steering wheel rim produced from such a blank.
Hitherto, various types of steering wheel core structure have been proposed. For instance, Japanese Utility Model Laid-Open Publication No. 104368/1985 discloses a steering wheel core structure composed of a hollow rim core having a groove formed in an outer surface thereof and web-like spoke cores having outer ends fitting in the groove and connected to the rim core.
This steering wheel core structure provides an appreciably high level of connection between the rim core and the web-like spoke cores. Unfortunately, however, this type of rim core cannot be combined with different types of spoke cores having different thicknesses. Namely, when web-type spoke cores of different thicknesses or rod-type spoke cores are to be used, it has been necessary to prepare a different rim core having a groove which is sized to receive the outer ends of a spoke core of a different type. In addition, when a rod-type spoke core is used, the rim core is required to have a groove of a width which is large enough to receive the ends of such a spoke core, with the result that the diameter of the section of the rim core is increased.
Another type of steering wheel core structure is proposed in Japanese Utility Model Laid-Open Publication No. 57171/1981. In this structure, spoke cores are connected to a rim core by means of brackets or pipe members so as to assure a high strength of connection between the spoke cores and the rim core. This type of core structure, however, necessitates an increased number of parts to be employed due to the use of the brackets or pipe members, so that the cost of the steering wheel is raised undesirably.
Thus, the first-mentioned known steering wheel core structure employing a rim core with a groove sized to fit to the end portions of spoke cores suffers from a disadvantage that the production cost of steering wheels is raised because it is necessary to prepare rim cores having different groove sizes. The second-mentioned known steering wheel core structure which employs brakets or pipe members also encounters a problem that the production cost is raised due to the use of a number of parts.